• Transactions of the Korean Society of Automotive Engineers
• /
• v.1 no.2
• /
• pp.34-41
• /
• 1993

In order to reduce harmful substances such as particulates and nitric oxides emitted from diesel engine, man kinds of methodology like high pressure spray of diesel fuel oil, exhaust gas recirculation, emulsified fuel usage and dual fuelling have been studied. Dual fuelling of a diesel engine with hydrogen which is well-known as the clean fuel and has excellent combustibility is expected to be effective in reducing harmful substances from diesel engine. This experimental study was conducted to investigate the effect of premixed hydrogen with intake air on the performance and particulate emission characteristics using a single cylinder, prechamber type diesel engine. As a result, it was clarified that a hydrogen-premixed diesel engine can be operated in the state of lower particulate emission and slightly aggravated fuel economy, compared with the conventional diesel engine.

• Journal of Photoscience
• /
• v.6 no.3
• /
• pp.103-108
• /
• 1999

We present recent results on ablation mechanism, single-pulse laser micropatterning , pulsed-laser deposition(PLD) and particulates formation accompanying laser ablation, with special emplasis on polymers, in particular polymide, (PI), and polytetrafluoroethylene, (PTFE). Ablation of polymers is described on the basis of photothermal bond breaking within the bulk material. Here, we assume a first order chemical reaction, which can be described by an Arrhenius law. Ablation starts when the density of broken bonds at the surface reaches a certain critical value. Single-pulse laser ablation of polyimide shows a clear-length dependence of the threshold fluence. This experimental result strongly supports a thermal ablation model. We discuss the various possibilities and drawbacks of PLD and describe the morphology, physical properties and applications of PTFE films.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.12
• /
• pp.1249-1256
• /
• 1997

Single phase La1-xSrxCoO3 (x≤0.2) was synthesized as a uniform sized 100 nm particulates with relatively high surface area of 20-30 m2/g, at low temperature (≥600 ℃), from a polymeric gel precursors prepared by using poly(vinyl alcohol) as homogenizer. No minor phase developed during the crystallization when polymer/metal mole ratio was higher than 3. As the polymer/metal mole ratio was raised in the gel, the amount of carbonaceous residues in the amorphous solid precursor prepared by heating the gel at 300 ℃ increased. Most of the residues were eliminated by exothermic thermal decomposition around 400 ℃. The amount of residual carbon (less than 1%) left in the crystalline La1-xSrxCoO3 decreased as more polymer was used, eliminating detrimental effect which might be posed by using large amount of organic homogenizer. The crystal structure of La1-xSrxCoO3 synthesized at temperature lower than 800 ℃ was observed to be shifted from rhombohedral to more symmetric cubic. The structure shifted back to rhombohedral as the cubic sample was annealed at 1000 ℃.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.275-282
• /
• 2008

This paper presents numerical investigation of multi-phase flow in solid rocket motor nozzle and effect of multi-phases on the performance prediction of the Solid Rocket Motor. Aluminized propellants are frequently used in solid rocket motors to increase specific impulse. An Eulerian-Lagrangian description has been used to analyze the motion of the micrometer sized and discrete phase that consist of the larger particulates present in the Solid Rocket Motor. Uniform particles diameters and Rosin-Rammler diameter distribution method has been used for the simulation of different burning of aluminum droplets generating aluminum oxide smokes. Roe-FDS scheme has been used to simulate the effects of the multi-phase flow. The results obtained show the sensitivity of this distribution to the nozzle flow dynamics, primarily at the nozzle inlet and exit. The analysis also provides effect of two phases on performance prediction of Solid Rocket Motor.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2003.06a
• /
• pp.66-75
• /
• 2003

This paper reviewed available information/data compiled by various agencies, institutions, and experts, including the academe. The review concentrated on five of the most pressing problems such as air pollution, water pollution, land pollution related to the problem of solid wastes, toxic and hazardous chemical wastes and deforestation. Most of the data presented focused on Metro Manila. Past air monitoring data showed significant exceedances of national air quality guideline values especially for particulates and lead. Many of the country's rivers and lakes have deteriorated, some were declared biologically dead. The acute solid waste problem and the proliferation of toxic and hazardous chemicals have led to the enactment of legislation. Uncontrolled deforestation has taken its toll on the environment and people. Various actions were undertaken by the national administration with the cooperation of other sectors to address environmental problems. However, constraints to the enforcement of environmental laws and programs must be minimized to attain the desired level of environmental protection and management.

• Journal of Korean Society for Atmospheric Environment
• /
• v.5 no.1
• /
• pp.79-87
• /
• 1989

In order to reduce the smoke emission from the in-service city bus, this study was evaluated the particulate reduction efficiency and regeneration ability of the catalitic trap oxidizer (CTO) on the city bus (D0846HM engine) equipped with it. Before the on-road CTO test, the laboratory test of CTO on engine test-bench was performed. Reduction efficiencies of smokes and particulates were 54 and 45%, and those of gaseous pollutants such as carbon monoxide (CO) and hydrocarbons (HC) were 90 and 60%. In order to evaluate the regeneration ability of the CTO by the catalytic oxidation of trapped particulate, field test was performed on the in-service road. The regeneration temperature was 350$^\circ$ which was same with the exhaust temperature of city bus.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.116-117
• /
• 2021

This study examined basic mechanical properties by developing eco-friendly soil concrete using Masato particulate matter treated as waste. Experiments show that DG10 satisfies the compressive strength criterion, but for DG20, the criterion was not reached. As the mixing volume of Masato particulates increased, the compressive strength and slump decreased, and in the case of the compression strength test after freezing and melting, it was found that the standards were not met.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.122-123
• /
• 2021

This study examines the performance of pretreatment process system as the initial construction stage of the pretreatment process system to use CGS, a by-product generated in IGCC, as a concrete fine aggregate of construction materials. The process undergoes a grinding process capable of grinding to a predetermined particle size during primary grinding and a sorting plant through sieve grading of 2.5 mm or less for particle size correction. Afterwards, it is hoped that the use of coal gasification slag of Korean IGCC as a fine aggregate for concrete will be distributed and expanded by producing quality-improved CGS fine aggregate using water as a medium for removing impurities and particulates.

• Asian Journal of Atmospheric Environment
• /
• v.5 no.3
• /
• pp.146-151
• /
• 2011

1-Nitropyrene (1-NP), 2-NP and 2-nitrofluoranthene (2-NFR) are useful markers for studying the atmospheric behaviors of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs). However, present methods for measuring trace levels of these compounds are lesssensitive and laborious. Here we describe several improvements to a previously reported high-performance liquid chromatography-chemiluminescence detection system that allows it to determine trace levels of 1-, 2-NPs and 2-NFR. The proposed system was equipped with a reducer column packed with Pt/Rh instead of zinc whose life-time was limited. The combination of Cosmosil MS-II (monomeric ODS) and AR-II (polymeric ODS) columns was used instead of polymeric ODS columns as the separator column to improve the separation. An ethanol mixture with acetate buffer (pH 5.5) was used in place of an acetonitrile mixture with the same buffer to activate the reducer column. The same ethanol mixture was used as the mobile phase for the clean-up column. The switching time of the column switching valve was optimized to concentrate the amino-derivatives of above NPAHs quantitatively on the concentrator column. The concentrations of bis(2,4,6-trichlorophenly) oxalate and hydrogen peroxide in the chemiluminescence reagent solution were optimized to 0.4 mM and 30 mM, respectively, to increase the sensitivity. Under the above conditions, the detection limits (S/N=3) of 1-, 2-NPs and 2-NFR were 1 fmol (0.25 pg), 10 fmol (2.5 pg) and 4 fmol (1 pg), respectively. The proposed system was effectively used to determine trace levels of 1-, 2-NPs and 2-NFR in airborne particulates collected at Noto Peninsula. The atmospheric concentrations of 1-, 2-NPs and 2-NFR were not more than sub pg $m^{-3}$ levels. They were higher in winter (January) than in summer (July). In both seasons, the concentrations were in decreasing order, [2-NFR]>[1-NP]>[2-NP].

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.4
• /
• pp.445-449
• /
• 2005

Present study was designed to evaluate the practical application of triethyl amine(TEA) injection for improving the collection efficiency of electrostatic precipitator(ESP) connected to a real operating plant. The major fuels used at the domestic power stations were bituminous coals imported from Australia, China, South Africa, and USA. Although the values of the electric resistance would be more or less different according to the type of the coals used, the unique electric resistance values of fly ash from the coals were mostly higher than $1{\times}10^{12}\;{\Omega}-cm$ and therefore, back corona problems were always expected to occur in the electrostatic precipitator. The particulates concentrations, smoke concentrations and their electric resistivity measured at the outlet of ESP, and the inspection of collection indicated that the injection of TEA improved the collection efficiency of particulate at collection plates of ESP. The electric resistance for, fly ash with the injection concentration of TEA 15 ppm(Purity 99.7%) was lowered to $2.1{\times}10^{11}\;{\Omega}-cm$ after injection from $1.9{\times}10^{12}\;{\Omega}-cm$ before injection. Under this condition, the dust emission content at the stack was reduced to approximately 80%, lowering the average outlet concentrations of particulates from $70\;mg/Sm^3$ to $14\;mg/Sm^3$.